Posted
by
Soulskill
on Wednesday July 22, 2009 @09:54AM
from the doomsday-averted-once-more dept.

suraj.sun tips this story at ZDNet about a new problem with the LHC. Quoting:
"The restart of the Large Hadron Collider has been pushed back further, following the discovery of vacuum leaks in two sectors of the experiment. The world's largest particle collider is now unlikely to restart before mid-November, according to a CERN press statement. The project had been expected to start again in October. To repair the leaks, which are from the helium circuit into the insulating vacuum, sectors 8-1 and 2-3 will have to be warmed from 80K to room temperature. Adjacent sub-sectors will act as 'floats,' while the remainder of the surrounding sectors will be kept at 80K, CERN said in the statement. The repair work will not have an impact on the vacuum in the beam pipe. CERN has pushed back the restart a number of times, as repair work has continued. To begin with, scientists said the LHC experiment would restart in April 2009. In May, CERN [said] that the restarted experiment could run through the winter to make up some of the lost time."

You laugh but that is exactly what a vacuum leak is. Air or some other gas leaks in and ruins the vacuum. Happens in auto engines causing performance problems there too. In the LHC they need a really good vacuum so that those hadrons can get up to a high speed which they won't do if they collide with gas molecules.

Hang around in a garage (where they work on cars, not where they park them) or a physics lab and you'll hear it often. Saying "vacuum leak" does not mean that vacuum leaks. By your reasoning, I should not be allowed to say "vacuum pump" either, since you pump the air out, you don't pump the vacuum. Tell me "vacuum pump" is bad English too. Go ahead.

Maybe history is repeating itself, if the first test they did caused some sort of temporal loop at the atomic level and that's what's been causing all the subsequent problems.

What, how many times? Dozens? Hundreds? You mean I've been working at the same job for over a century now, but only got about one year's worth of paychecks?! To hell with black holes destroying the Earth, that's nothing compared to this!

Masochistic is right. I just spent all of last week trying to find and fix a vacuum leak in my experiment. Luckily it was a (relatively) straightforward setup and after I got to the point where I wanted to strangle someone (or wreck the lab with a hammer - I'm not too fussy about my violent outbreaks:)) I just swore a terrible oath at the thing and machined a new one from scratch.

I'm not complaining about the work (it's sorta like having an irritating kid - no matter what, it's still your kid:)), but vacuum leaks can be seriously frustrating, especially the ones that show up with a delay so you have not the slightest farking clue where the damn thing is leaking.

Since I feel like venting (no pun intended:P), I'll let y'all in on just how one leak checks a vacuum chamber. The leak-checker is just a glorified pump that can pump down to really low pressures. The stuff coming out of the chamber is also directed into a mass spectrometer that is tuned to register and count (usually) helium atoms. You spray helium gas over the outside of the vacuum chamber and if there is a leak, some helium gets sucked in and registers on the spectrometer. The bigger the leak, the bigger the count and a simple calculation converts this into ccs of helium coming in per second with a pressure difference of 1 atmosphere across the leak (1 atm outside and ~0 inside) - that by the way is where the unit standard ccs per min (sccm) or standard cubic feet per min (scfm) comes from - you may have encountered these units in several diverse places (anywhere that gas flows are controlled through pipes). Of course, these days most of this is automated but we have this really cool leak-checker (Air Force surplus from the dawn of time:)) that is so freakin' awesome and not too automated. It's from the 60's and still works perfectly o.O

The bottom line is that finding a small leak* in a man-sized chamber is difficult to begin with. Imagine how insanely difficult it would be to do this in the frakking LHC! And there, since they deal with subatomic particles, they need even better vacua than I do. Gawd I'm glad I'm not the guy in charge of finding leaks - I'd probably start gibbering and running around in little circles if I had to deal with it:P.

____________________
*Here, small usually means somewhere around 1E-9 std.cc/s - at this rate, it would take more than 25 thousand years for a vacuum chamber the size of a beer stein to fill up due to air bleeding in from the outside. Much more than that actually since the rate would go down when the pressure difference decreases but this will do for now. And yet, such small leak rates can wreak havoc in delicate experiments (for instance, in a recent one where I was trying to measure the flow conductance of nanoholes - very tiny flows and leaks can screw things to hell).

I understand this being/. most people think that argh is just a pirate term, since there are so many RIAA stories. In the context of Physics, which is what this post is about, argh is an SI unit of work done incorrectly.

You could try some of the books by Frank Close. He's a British author and, while I've heard that some don't like his style, I appreciate it a lot more than Brian Greene - but then I work in the field so I might have a different point of view to a layperson.

I fail to see how someone who is humbly asking for sources of information on a topic which he would like to study in more depth can be classified a "know-it-all asshole", even in colloquial terms. Does anyone who enjoys the process of learning more than yourself constitute such a person?

But if you remove the large breaking block from the emergency exit tubes (the ones where the matter is sent to when something goes wrong. I don't know their name.), you can do this: http://xkcd.com/401/ [xkcd.com]

For science and humanity, surely you are right. This does effect those of us who work on it, however. People are waiting to graduate, waiting to publish, waiting to move on to other things (at the LHC or elsewhere). Scientists sometimes like to have normal lives too, and not have their careers stalled out.

Not to mention, the number of people who get tired of waiting and leave increases as time goes on (this does happen, there's plenty people switching over to D0 and CDF theses), depleting the amount o

To paraphrase, this guy is in the middle of a flooding city. He repeatedly refuses attempts of others to rescue him, claiming God will save him. He drowns, winds up in Heaven, and asks God why he didn't save him. "I sent you a two boats and a helicopter..."

So I can see God now using his mighty and flagellant tendrils to tinker with the LHC's inner workings and yet we still press on, thwarting his every attempt to save the planet Earth and the life he created. I'm certain this will all end with a, "Okay, power it up!", followed by a surprisingly brief sucking sound as the world is drawn into a black hole of its own making.

Holy crap! If this continues that monster could leak enough vacuum to completely cover the entire world, possibly destroying all life on Earth. How long are these madmen going to keep playing with dangerous things like vacuum before somebody puts a stop to it all?

Think about what it takes to work on that thing. It's in a long underground tunnel of rather small diameter for what's in there. Fixing stuff in place is difficult and hazardous. Removing a magnet involves disconnecting everything (a big deal; some of the connections are welded and superconducting), lifting the magnet onto a narrow carrier that runs on the walkway (no idea how that's actually done) and inching the carrier for kilometers to one of the two big vertical shafts where it can be hoisted out vertically. As an underground maintenance job, this is not fun.

The canceled American SSC was designed with a larger tunnel diameter. The LHC was designed with the assumption that not much magnet maintenance would be required, which cut costs but turned out to be a bad assumption.

What's worrisome is that these same scientists who can't seem to build this thing without some fatal flaw are the same scientists telling us there's nothing to worry about when they create a black hole.

Sorry if I'm missing intended humor in your post but that just doesn't make any sense.

These are construction flaws. The fact that the black holes they may be able to create are not a threat has nothing to do with any sort of special containment. It's simply that the size and level of energy is no where near enough to last even nanoseconds.

The ignorance about the dangers of particle accelerators is disconcerting.

By the way, if you want a good look at modern physics, read Brian Greene's "The Fabric of the Cosmos". Really good read.

The ignorance about the dangers of particle accelerators is disconcerting.

Said the pot to the kettle.

The purpose of designing the LHC was to see what happens because they don't know what happens, and you are just as ignorant as the person you're chiding. No one is an expert on what happens when the very underlying principle of the experiment is that "no one is sure what will happen". It could make delicious, expensive icecream, for all we know. It could, in theory, destroy the world or a part of it. Given the evidence, I don't THINK it will destroy the world, but giving rid

You're sort of incorrect here. Yes, we built the LHC to probe a new energy regime. However, much MUCH higher energy collisions occur in the atmosphere every day. If we could place multimillion dollar particle detectors like ATLAS and CMS in the atmosphere, we would.

So you could say that we know what definitely will not happen; the world will not be destroyed. I have proof: we're here today to discuss the subject. Since the Earth has been around for some billions of years and these types of events are f

It could make delicious, expensive icecream, for all we know. It could, in theory, destroy the world or a part of it. Given the evidence, I don't THINK it will destroy the world, but giving ridiculous odds against it (like winning the lottery 10 times in a row) is outright lying.

For all you know, sure, maybe the LHC will turn into a pack of Tyrannosaurs with opposable thumbs and big T-Rex sized mopeds that will terrorize the countryside.

Physicists don't know exactly what happens as a result of collisions li

They're attempting to create black holes. There aren't "controlled circumstances" for that outside of "We'll keep it really cold and we'll only make little ones."

No, they're not. And "Controlled" means an environment where they know that the only collisions are the one they create, and where the impact occurs in a vacuum surrounded by large amounts of highly sensitive detectors. The "uncontrolled" version happens constantly, yet here we are. Hard to comprehend, I know, but not surprising for someone who

What's worrisome is that these same scientists who can't seem to build this thing without some fatal flaw are the same scientists telling us there's nothing to worry about when they create a black hole.

These are construction flaws. The fact that the black holes they may be able to create are not a threat has nothing to do with any sort of special containment.

What's worrisome is that these same scientists who can't seem to build this thing without some fatal flaw are the same scientists telling us there's nothing to worry about when they create a black hole.

The scientists blame the engineers. But let's see who gets "credit" for the Galactic Darwin Award.

What's worrisome is that these same scientists who can't seem to build this thing without some fatal flaw are the same scientists telling us there's nothing to worry about when they create a black hole.

No, what's worrisome is that the murderous idiocy of self-serving show-offs is so persistent.

How many people do you have to kill before you'll stop promulgating this stuff?

An emotionally unstable teenage girl in India killed herself because she was so terrified that the world was going to end when the LHC turned on. I assume you're extremely pleased with that outcome, as it is the only concrete effect that the efforts of people like you to propagate this vicious nonsense has had.

There are giant amounts of particles with way higher speeds colliding with our atmosphere all the time, creating the same type of black holes.The type that is apparently so unstable, that all those particles did not create one single black hole that are us all.Go figure.

And try to not get your "knowledge" from the loudest and dumbest of all people.

This is the USA that you're talking about, right? To the extent this physics knowledge is in the Bible, such efforts are unnecessary expenses. To the extent the knowledge is not in the Bible, such efforts are forbidden.

The explosion happened last September, so it can't be a year behind the new schedule; it hasn't even been a year since the explosion! The schedule set after the explosion was to run again the following September, so it's now predicted to be 2 months behind that schedule

And it's really not too bad, since the SSC was far more overbudget than the LHC has ever been and was being footed solely by the US (whereas the LHC is international). And we're not really losing anything from even a one-year delay. Also,

Particle interactions with more energy than LHC can produce happen in the Earth's atmosphere every day. But outside of a carefully controlled environment with extensive sensor equipment, they can't be studied. The LHC is not about creating energies never before seen on Earth-- it won't do that. It's about doing so in an extremely controlled manner than can be measured and investigated.

I was at Fermilab yesterday and a video they showed claimed they ARE working with energies never before seen on Earth, as they are smashing antiprotons into protons, both going near the speed of light. Yes, there are higher energy PARTICLES contained in cosmic rays. Perhaps the video, being old, doesn't account for some recent discovery of naturally-occuring antimatter, but otherwise I don't think anything in nature (around Earth) can reach the energy of two high-speed hadrons converting into energy- at lea

After an authoritative-sounding bunch of complete nonsense you say: but not being familiar with quantum physics...

Well, given you know you aren't familiar with it, why are you telling us what kind of experiments are going on in it?

It is possible, perhaps, that not being familiar with the subject matter you completely misunderstood the PR hype from Fermilab, which certainly does not produce collisions with energies that are anywhere close to what is happening in the atmosphere every day?

After an authoritative-sounding bunch of complete nonsense you say: but not being familiar with quantum physics...

Reading articles on wikipedia, written by college dropouts, doesn't put you at any higher level than he is.

every competent physicist who has rightfully dismissed the... "LHC's gonna make a black hole" crowd

The point of the LHC is to make a black hole. Physicists claim it will dissipate quickly enough from the Hawking radiation vs. whether it will begin snowballing out of control. NOT whether it will create one. You don't even know what you're talking about.

If you start a small firework rocket, you can't predict how far up it will fly and when exactly it will blow up in a shiny and entertaining explosion. But you know the limits of that rocket, e.g. it won't fly up more than 200 feet, the light of the explosion won't last longer than 10 seconds and it won't get hotter than 150 degrees celsius in the center of the explosion (numbers completely made up by me).

The scientists know that the black hole and anything else that may come from LHC won't destroy the wo

As others have said, we already know that earth-destroying events (black holes, whatever else) can't be created at the LHC because we're still here to talk about the possibility. If the LHC could make an object that destroys the world, then that object would have already been produced by atmospheric collisions and we'd be dead right now.

One thing I've never understood about this explanation is that it doesn't explain why it's always the anti-particle that falls into the black hole. Wouldn't chance dictate that half the time it will be the particle, causing the black hole to take on the extra mass?

(I'm sure the answer to this question is somehow related to a similar question that I've always had... and that is: why is the universe composed almost entirely out of matter rather than being a mix? and why aren't there any anti-matter black ho

All of science is based on an assumption namely that the laws of nature do not change. You cannot prove that tomorrow gravity will continue to work as it did today. However given that, as far as we can tell, gravity seems to have worked since the Big Bang, it seems a very reasonable assumption that it will continue to work tomorrow.

So saying that things are based on assumptions is meaningless unless you state what those assumptions are and what evidence there is to point out that they are wrong. Otherwis

There may in fact not be any; it's possible that life (and the conditions that cause it) is so rare in the universe that only one in a hundred galaxies has produced it

It's too far away to talk to. No other civilizations farther than a little more than 100 light years away would have been able to pick up any EMF we transmitted

The signals we/they transmit are likely too weak to detect

It's possible that we haven't discovered their form of communication, while they haven't discovered ours

They may have seen our violent history (or their own) and are afraid to communicate with us. If I was them, I'd be scared, too.

They may not even realize we are alive (their form of life is likely to be more bozarre than we can imagine)

Our own hubris - many (most?) people don't realize that other species on our planet do in fact think, feel, and communicate. It's only recently that science has discovered that other species do in fact communicate

They may be so advanced that we're just not interesting to them

If present science are so sure about all possible consequences of creating black holes using Large Hadron Collider or any collider that size, than why any expirements needed ?

Because for a hypothesis to become a theory, it must be tested. That's how science works.

How people that are not "against science" can guarantee any HollyDolly mother, that she's childs are in safe place

There is no such thing as absolute safety. Your "1%" chance enormously overestimates the chances of a black hole swallowing the earth. We're not talking about a pea sized black hole (which would have a mass as great as a mountain), but an infinitessimal mass measuring the same as a few atoms, at most.

Information can enter black hole but can't escape.

See, the problem is calling these tiny singularities "black holes". Wikipedia's definition of "black holes" excludes these things. There is a vast difference between a gnat and an elephant, even though both are animals. There's no magic about black holes swallowing light; in space an object must have enough mass to collapse on itself to create a black hole, if I remember correctly it's about the mass of a thousand suns.

You have far more dangerous things to worry about, driving your kids to the store for instance.

I think #8 is a bit of a red herring (along with some of the others, but particularly #8). Our complexity or lack thereof does not reduce our value as a data point for determining how life typically evolves in the universe. For that reason alone any one/thing interested in exploration would be interested in us, and other life forms on our planet, the same way we're interested to know if there's simple life on Mars.

That's not really a good metaphor because it implies similarity between all colonies. If the ants in your backyard were demonstrating a behavior different than any other ants studied, then a biologist would certainly be interested.

Really, regardless of the starting assumptions, someone would be interested in us, if they exist:

1) If we assume that Homo Sapiens exist on other planets (colonies) that are identical to us, then those people would be interested in us, and the super-intelligent species is irrele

Once it 'works' . . . my guess is something will go wrong with the measuring instruments. There's no reason to think that the base functionality is the only thing flawed. It'll be great to finally have particles fire around the track, collide, and have bad data.

Cutting-edge science uses cutting-edge technology.Of course it breaks !But in a few decades these technologies might be ready for industrial uses.

This is a giant multi-national project with funding from multiple governments. I'm sure there was plenty of politics and bureaucrats involved, not just a bunch of over-ambitious engineers trying to build the most complicated things they could dream up.

Yes, right now the tevatron [wikipedia.org] at Fermilab [wikipedia.org] is superior to the LHC, and it's half as big as your 12 km and most likely as complex as the LHC. It may in fact be years before the LHC comes on line, but I have no doubt that it will come on line.

The LHC will tell us things that the Tevatron can't when it does come on line. It will be well worth the wait.

This is why movies have producers. It's to keep the artists in check. Someone should have kept the brains in check when they designed this thing. Instead of being smaller and useful, it's just a gigantic waste of money -- the Waterworld of the scientific community.

Yes, and we should dismantle Hubble and replace it with an army of hobbyist astronomers with a 100$ telescope. They won't find anything new except maybe a few near-earth asteroids, certainly no exoplanets and all the other interesting stuff happening. Same with LHC, if you wanted any particle accelerator I think we had an electron one in high school science class. We could play with it forever but I doubt we'd ever get any more results on the standard model and the higgs particle. Experimental science of this kind is all about building the most sensitive equipment you can - it's complex, expensive, obsoleted by the next generation but it's the only way to do science and not guesswork.

Couple of things - this wasn't redundant when I wrote it - by the time I had come back to the main thread two other people had mentioned it. I *did* actually check first - I hate being redundant. Secondly, if you read the moderation recommendations, you are supposed to use mod points in general to mod up. If I see something redundant, I don't waste mod points on it, I simply don't mark it up. Simple really. Think about it next time.

Yes - but you need "duct tape" that works at -271C and you need to warm up the magnet first so you can open it up to put it there and then cool it down again. You have to do this very slowly (~month) so that everything can expand and contract together.